A HVAC system generally includes a compressor, heat exchangers such as a condenser and an evaporator, and an expansion device. Generally, in a cooling mode, the compressor can compress refrigerant vapor. The refrigerant vapor may be directed into the condenser to be condensed into liquid refrigerant. The liquid refrigerant may be directed into the evaporator through the expansion device to become a two-phase refrigerant mixture and reduce its temperature. In the evaporator, the refrigerant can exchange heat with a process fluid, such as water or air.
The heat exchangers can have various types and configurations. In some HVAC systems, such as a chiller, a commonly used heat exchanger is a shell and tube type heat exchanger. The shell and tube type heat exchanger generally has a tubes-inside-a-shell configuration. A shell side and a tube side are generally configured to be in a heat exchange relationship and carry two different fluids. For example, in an evaporator, the shell side can be configured to carry refrigerant and the tube side can be configured to carry the process fluid, such as water. The refrigerant can exchange heat with the process fluid so as to regulate a temperature of the process fluid. For a heat exchanger that works as an evaporator, commonly used shell and tube types of heat exchanger can be a falling film, or flooded evaporator.